Oilfield systems are subjected to increased risks associated with microbial control including: H2S production, microbial influenced corrosion (MIC) and biofouling. When MIC is suspected in a system, the main area of concern becomes the biofilm, or sessile organisms, on the surface of the pipeline. It is widely recognized, within the industry, that in order to be effective at controlling the bacteria within a system there should be a focus on minimizing biofilm regrowth kinetics following treatment (sessile control) in addition to providing sufficient planktonic kill. While use of biocides such as tetrakis-(hydroxymethyl) phosphonium sulfate, glutaraldehyde, and quaternary ammonium compounds are used to delay the regrowth kinetics of biofilms, there is an increased need to identify biocides or combination of biocides that provide the most efficient performance means for microbial kill and biofilm control, and in particular, penetration and delay in the regrowth kinetics of biofilms.
Current biocide performance testing relies on classical microbiological culturing techniques and other non-culture based methods such as ATP photometry and fluorescence microscopy. For field monitoring of microorganism growth in oilfield systems, the standard test method is the NACE International Standard Test Methods, which is fully incorporated herein by reference. These methods include membrane filtration methods for assessing bacterial populations, culturing by serial dilution, and alternative sulfate reducing bacteria (SRB) media growth methods. These methods have drawbacks due to delays in culturing oilfield bacteria that can take as long as two to four weeks to incubate and grow, thereby delaying biocide performance optimization. Non-culture based methods such as ATP photometry reduce the time for biocide optimization, but do not always measure all microbes in a particular isolation because these methods cannot identify microbes that are dying, but have not lysed or the membrane are still intact.
Accordingly, despite the available technologies, there remains a need for measuring biocide performance and synergies for efficient use in oilfield and other applications (e.g., food industry, paper industry, water purification, waste water treatment, etc.). This method would provide quick analysis of bacterial populations in particular isolates (e.g., oil field samples), absolute quantification of dead microbes, and insight into biocidal mechanisms of action via amount of time to apply the biocide, concentration of the biocide and preferred combinations of different biocides to identify chemical/biological synergies.